Sheet material punch gun



Feb; '10, 1970 L,.1E. YoHo El AL SHEET MATERIAL PUNCH sun 5 sheets-sheet1 Filed. Oct.

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Feb. 10, 1970 L. E. YOHO ETAL SHEET MATERIAL PUNCH (EUR 3 Sheets-Sheet 2Filed Oct. 9. 1968 H W T D ON 5 mYA v .R I x N P R D 0 NM W A6 A vm HR.L

Feb; 10, 1970 g, YQHQ EI'AL 3,494,431

SHEET MATERIAL when GUN Filed Oct. 9, 1968 I 3 Sheets-Sheet 5 no mmUnited States Patent 3,494,431 SHEET MATERIAL PUNCH GUN Leland E. Yoho,3391 State Rte. 43, Mogadore, Ohio 44260, and Harrison P. Randolph, 3389Wyoga Lake Road, Cuyahoga Falls, Ohio 44224 Filed Oct. 9, 1968, Ser. No.766,116 Int. Cl. B26f 1/34; B25d 17/00 US. Cl. 173119 Claims ABSTRACT OFTHE DISCLOSURE Apparatus for punching holes in sheet materials and thelike having a spring driven piston housed in a cylindrical bore of theapparatus, a punch which is housed in a second bore, the two boresaxially communicating to the extent that the forward portion of thepiston is movable into the punch bore. The punch is maintained biasedoutwardly by a second spring so that the piston cannot contact the punchunless the punch is depressed to overcome the biasing force of thesecond spring. A cocking means selectively orients a sear plate againsta collar on the piston so that actuation of a trigger means whichengages the sear plate causes the release of the piston which willstrike the punch when the punch is depressed against an object.

BACKGROUND OF THE INVENTION This invention relates to an apparatus usedprimarily for punching holes in sheet metal and other durable sheetmaterials. The apparatus is constructed to allow an easier and saferpiercing of the object being worked on, and is capable of varying thesize of the opening made.

The sheet metal working art, involving the installation of ducting forheating and air conditioning purposes and other projects requiring thata hole be placed in sheet material, has a long existing requirement fora portable, safe, and rapid operating punching device. Heretofore, themost efficient method of piercing sheet metal and the like was to use adrill powered by electricity, air, or other source of energy. However,the use of the power drill has many disadvantages, one being that itsarea of use is confined within the transmission limits of the powersource. Thus, if it becomes necessary to work at a place remote from thepower source, as is often the case when working on scaffolding duringbuilding construction, a great deal of complex wiring or hosing may benecessitated, making it impossible or highly impractical to reach theremote source.

Other disadvantages of the electrically powered drills are the initialcost of the drills themselves and the cost of the power to operate them.It also becomes quite costly to replace broken drill bits, and tosharpen dull ones, for the drills must be quite sharp to penetrate eventhin samples of hard materials. If the drill is not sharp, more pressuremust be applied by the operator, thus often causing premature drill bitbreakage. Even with a sharp drill bit, the drilling process is oftenslow and tedious, for the operator must be quite careful in preciselylocating the bit (using a starter or pilot hole on heavy sheeting),applying just the right amount of pressure to assure accurate placementof the bit, and then maintaining that pressure throughout the drillingperiod which may be an appreciable time interval. Finally, while the useof a power drill eventually makes a clean hole, this too has itsdisadvantages in that if a screw is to be threaded into it, there is aminimum of surface for the threads to engage.

On jobs where it is impossible to reach a power source, or on low-budgetjobs where power equipment is not justified, the workman must use ahammer and punch 3,494,431 Patented Feb. 10, 1970 to place the desiredhole in the sheet material. This method is also used on jobs wherescrews are to be threaded into the holes, because the hammer and punchprocedure will not leave the clean hole as produced by the drillingdevices, but rather create a flared portion on the back side of thematerial to which the threads of a screw can grasp. However, the hammerand punch method also has inherent disadvantages. First, it takes agreat deal of physical labor and time to pierce hard materials,particularly a thick sheet of metal, by this hand process. The punchmust be battered by a hammer a number of times for each of the largequantity of holes usually required with the attendant risk of missingthe punch, thereby injuring the hand of the workman or damaging thematerial.

Another disadvantage of this hand method is that the laborer must haveroom to swing the hammer. Often when working on ducting in confinedareas, there is insufficient room to move the hammer with enough forceto penetrate the material, therefore necessitating repeated strokes.Then too, where there is room to swing the hammer, the location of thework relative to a scaffold or ladder, may require extreme extension ofthe workmans body so that he must take care not to lose his balancewhile trying to exert enough force to achieve penetration with thepunch.

A further disadvantage to the manual hammer and punch system is evidentwhen working on thin sheets of relatively hard materials. In thisinstance, while less strokes of the hammer are required, the relativelydull nature of the punch, combined with the slow rate of travel of thepunch through the material will cause an unsightly indentation ordishing of the material around the hole.

All of the aforementioned problems are further compounded when rivets orthe like are to be used as the fastening means in the hole. In thissituation additional tools and/or more strokes of a hammer are requiredto secure the rivet in place.

Some of the above problems have been solved by the development ofportable center or marking punches; however, these devices are notcapable of completely piercing the sheet material. For example, one typeof marking device presently used has a cylindrical housing having thepunch protruding at one end with an intricate and delicate cockingdevice therein, so that when the user grasps the body of the device anddepresses the point against the object to be marked, the device cocksand fires in the same motion. However, devices of this nature areinherently limited to marking functions and do not contemplate piercing.

Other center or marking punches are concerned with self-cocking orone-finger operation features which are inherently impossible in thepunch art where the material is to be completely pierced. Further, thecenter marking devices do not concern themselves with all the problemsof the punch art, such as safety, hole alignment, and impact regulation,since the objectives of each type of device are radically different.

SUMMARY OF THE INVENTION It is, therefore, an object of the presentinvention to provide a device for punching holes in sheet metal and thelike that is capable of complete, rapid penetration of even the heaviestof such materials.

It is another object of the present invention to provide a punchingdevice which fires only if actuated after depression of the punch pointas a safety feature.

It is still another object of the present invention to provide apunching device, as above, which allows accurate placement and retentionin the desired position for the hole.

It is yet another object of the present invention to provide a punchingdevice, as above, which provides regulation of the impact of the punchand thus controls the size of the hole.

It is a further object of the present invention to provide a punchingdevice, as above, which is inexpensive to maintain and operate,relatively safe from the hazards of prior devices and completelyportable in not requiring an outside power source.

It is a still further object of the present invention to provide apunching device, as above, which can create a hole suitable forreceiving a screw without denting the material.

It is even another object of the present invention to provide a punchingdevice, as above, which requires a minimum of physical labor to operate.

It is an even further object of the present invention to provide apunching device, as above, which can be adapted to rivet driving andother similar uses.

These and other objects which will become apparent from the followingspecification are accomplished by structures hereinafter described andclaimed.

In general, a sheet metal punching device constructed according to theconcept of the present invention comprises a gun-like housing havingbores containing a spring driven piston and separate punching point. Thepunch point rides in a cylindrical bore near the tip of the gun housingand is biased outwardly by a small spring. The piston, which rides inanother bore, has an enlarged collar portion near the forward end whichserves to provide a rear shoulder, behind which rests the large drivingspring, and a front shoulder which provides a stop surface for thepiston. The piston bore and the punch bore communicate to a degree suchthat the end of the piston strikes the rear of the punch when the latteris depressed.

Also communicating with the piston bore is a sear plate which is urgedtoward the piston by a wire spring so that when the piston is forcedrearwardly by a cocking means, the sear plate will move into position infront of the stop surface shoulder against the collar portion of thepiston. The preferred cocking means shown is a hinged split handlewhich, when divided, draws the piston straight back, compressing thespring. A trigger device rests against the sear plate in such a mannerthat the sear, which is holding the piston back when the gun is cocked,supplies a certain amount of tension to the trigger. A mere pulling ofthe trigger moves the sear to release the piston which drives the punchforward at a high rate of speed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation view,partly broken away and partly in section, of the preferred embodiment ofthe sheet metal punch gun according to the present invention showing theoperation of the split handle for cocking the mechanism in chain lines.

FIG. 2 is a top plan view of the sheet metal punch gun depicted in FIG.1.

FIG. 3 is an enlarged cross-section of the punch gun of FIG. 1 with themechanism in the uncocked state.

FIG. 4 is a view similar to FIG. 3 depicting the preferred embodiment ofthe invention in the cocked state, ready to fire, after actuation of thesplit handle as depicted in chain lines in FIG. 1.

FIG. 5 is a fragmentary sectional view taken substantially along line 55of FIG. 3 and showing the pivotal attachment of the bifurcated handle.

FIG. 6 is a fragmentary sectional view taken substantially along line 66of FIG. 3 and showing the sear plate and related components.

FIG. 7 is a fragmentary sectional view of the punch member of thepresent invention as adapted for the function of driving rivets.

4 DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings andparticularly FIGS. 1-4, punch gun apparatus for piercing holes in sheetmaterials and the like according to the present invention is indicatedgenerally by the numeral 10. The major portion of gun 10 is a barrel orhousing, generally indicated by the numeral 11, containing an elongatecylindrical bore 12. The bore 12 is of uniform diameter through aportion of its length and has, preferably toward the front of barrel 11,a reduced neck portion 13 which flares outwardly to form a punchreceiving bore 14 at a surface of barrel 11. Proximate the punchreceiving bore 14, a punch housing generally indicated by the numeral 15is attached to barrel 11 as by threads 16 and has an axial through bore17 and a counterbore 18 which communicates with and is preferably thesame size as punch receiving bore 14. When punch housing 15 is threadedonto barrel 11, bore 12, neck portion 13, punch bore 14, through bore 17and counterbore 18 are all axially aligned, for reasons more fullydiscussed hereinafter.

Housed within bore 12 of barrel 11 is a piston 19 which may be ofsubstantially uniform diameter with a portion slightly smaller than thatof neck portion 13 of barrel 11. Piston 19 is provided with a collar 20,which may be near the front end thereof, forming a forward shoulder 21and a rear shoulder 22. The travel of piston 19 within bore 12 isrestricted in the direction toward punch housing 15 by the forwardshoulder 21 engaging a stop surface 23 formed by neck portion 13 in bore12. A coil spring 24 encases piston 19 and is interposed between rearshoulder 22 of collar 20 and an insert 25 at the rear extremity of bore12. Insert 25 is provided with a bore 26 to permit passage of a portionof piston 19. The piston 19, forward of collar 20, forms a ram 27 which,as previously discussed, is insertable into neck 13 and may extend adistance into punch receiving bore 14.

Substantially housed within by punch receiving bore 14 and punch housing15 is a punch, indicated generally by numeral 28, which may be generallycylindrical. The punch 28 consists of a blow-receiving base 29 and anenlarged collar 30 which may taper inwardly at its forward end to form apunch shaft 31. Shaft 31 is adapted to be slidably received within thethrough bore 17 of punch housing 15, while the collar 30 slidablyengages punch bore 14 in barrel 11 and counterbore 18 of punch housing15 to maintain punch 28 suitably aligned. The shaft 31 has a tip portion31 which normally protrudes from housing 15, as shown in FIGS. 1 and 3,and is normally maintained biased in this outward position by a coispring 32 which fits around the blow-receiving base 29 and is interposedbetween a flared shoulder 33 formed by neck portion 13 and a rearshoulder 34 of collar 30. It should be noted that when the punch 28 isin the extended position, as in FIG. 3, the tapered shoulder 35 of punchcollar 30 is engaged by a stop surface 36 of punch housing 15 at thetermination of counterbore 18.

Referring particularly to FIGS. 3, 4, and 6, the lower portion of thebarrel 11 is provided with a slot-like cavity 38 which communicates withbore 12 via a segmental aperture 39 located generally toward the forwardend and at the bottom of bore 12 and extending approximately the widthof cavity 38. Positioned within cavity 38 is a sear plate, indicatedgenerally by the numeral 40, being pivotally mounted therein on a pin 41which is journalled in housing 11. Sear plate 40, as shown, iswedge-like in shape, flaring outwardly rearwardly, and terminating in anupwardly oriented cocking flange 42 being in the general area ofaperture 39. The sear plate 40 also has a lip 43 extending rearwardlyfor a purpose to be described hereinafter. Also partially housed incavity 38 is a trigger, generally indicated by the numeral 44, beingpivotally mounted on a pin-45. The trigger is preferably a somewhatelongate member having a handle 46 extending outwardly of barrel 11 anda projecting shoulder 46 within cavity 38 which selectively engages lip43 of sear plate 40 as described more fully hereinafter.

As best seen in FIG. 6, a small wire spring 47, which may be somewhatU-shaped, rests against the bottom of sear 40 so that it is biasedgenerally clockwise (-FIGS. 3 and 4), cocking flange 42 thus beingcontinually urged toward opening 39 in bore 12. Spring 47 has an anchorflange 48 (FIG. 6) at each extremity, each having a prong-like foot 49(FIGS. 3 and 4) thereon. Anchor flanges 48 rest in slots 50 in theunderside of housing 11 on each side of cavity 38. The outward ends ofslots 50, in turn, are provided with small holes 51 for receiving feet49. To accomplish the dual function of closing off cavity 38 and holdingfeet 49 of spring 47 in holes 51, a cover plate 52 is fastened tohousing 11 by screws 53 and positioned to clear trigger 44. The plate 52also provides ready access to the chamber 38 in the event that any ofthe components therein require maintenance.

To enable an operator to cock the apparatus disclosed herein, there isprovided a split handle 54A and 54B. As shown, handle 54B is formedintegral with barrel 11, while handle part 54A bifurcates at the topinto two forklike prongs 55 of substantial width, as best shown in FIG.2. Handles 54A, 54B are joined by a link 56 which is located betweenprongs 55 of handle 54A and upstanding space flanges 56' on barrel 11 atthe top of handle 54B being attached to each by pivot pins 57 and 58,respectively, for limited rotational movement.

Handle 54A is operatively connected to piston 19 by a bearing pin 59freely rotatably mounted in bushings 60 inserted in each of the prongs55 of bifurcated handle 54A. Bearing pin 59 has a bore 61 which slidablyreceives the piston 19 forward of a threaded portion 62 thereon. Thepiston 19 is moved rearwardly with handle 54A by means of a stop nut 63having a shoulder 64 of larger dimensions than the bore 61 of bearingpin 59. The travel of piston 19 during the cocking operation may bevaried as necessary by adjusting the position of the stop nut 63 on thethreaded portion 62 of piston 19.

The operating sequence of the punch gun apparatus may be traced from theuncocked position of FIG. 3 which would be the condition aftercompletion of an operating cycle. As shown, coil spring 32 ismaintaining punch 28 outward so that tapered shoulder 35 is restingagainst stop surface 36, the tip 32 being fully extended. At this stagetrigger 45 is at rest or untensioned, trigger shoulder 46' restingagainst lip 43 of sear plate 40, but cocking flange 42 barred from entryinto bore 12 of barrel 11 by the presence of coil spring 24 on piston19.

In order to cock the sheet metal punch gun 10 for another operatingcycle, an operator separates handle part 54A from part 54B, as shown inthe chain line position of FIG. 1 as 54A. The dual hinge nature of link56 provides a substantially straight back or linear travel of piston 19.During the beginning of the cocking movement, link 56 moves upward in anare centered on pin 58, as shown in FIG. 1 as chain line position 56".Continued movement of handle part 54A away from handle part 543 causeshandle 54A to rotate in an are centered on pin 57. Throughout this dualarc movement, bearing pin 59 is translated rearwardly against shoulder64 to move nut 63 and thus draw piston 19, rearwardly, compressingspring 24 until collar 20 passes opening 39. At this point, the searplate 40 is urged upwardly by spring 47 so that the cocking flange 42rests in front of shoulder 21 of collar 20 as seen in FIG. 4.Simultaneously, lip 43 of sear plate 40 moves trigger shoulder 44upwardly and pivotally in a counterclockwise direction about pin 46,thereby putting tension on trigger 45. With the gun thus fully cocked,handle 54A is returned to the position shown in FIG. 4, leaving the stopnut 63 on the end of piston 19 extending rearwardly away from bearing59.

The gun having been cocked, an operator places the tip portion 31' ofpunch 28 at the desired position for penetrating the material, depressesthe tip portion until it is flush with the punch housing 15, and movesthe trigger handle 46 toward the handle 54B. FIG. 4 shows the gun beingprecisely aimed by the depression of punch 28 against the workpiece,thus compressing spring 32. A rearward pull of trigger 46 rotates thatmember in a clockwise manner around pin 45 which, in turn, rotates searplate 40 in a counterclockwise direction around pin 41 overcoming theresistance of wire spring 47 and moving flange 42 downwardly andoutwardly through opening 39 to release piston 19 which is drivenforward by spring 24. Ram 27 thus contacts base 29 of punch 28 forcingtip portion 31' completely through the workpiece, as shown in chain lineposition 31" of FIG. 4. Should partial penetration or a lesser force bedesired, the operator depresses punch 28 only a portion of the way tothe fully depressed flush position. Punches 28 of appropirate size andphysical characteristics may be substituted by merely unscrewing thepunch housing 15 and inserting an appropriate punch 28.

It is evident that even if the gun were cocked as described, were punch28 not depressed against a workpiece, a subsequent pulling of thetrigger would not move punch 28 because, as shown in FIG. 3, spring 32maintains shoulder 35 of punch collar 30 against stop surface 36 ofpunch housing 14 and shoulder 21 of piston collar 20 engages stopsurface 23 of barrel 11, thus stopping ram 27 prior to striking punchbase 29. This provides an important safety feature in that accidentaldischarge when the punch 28 is contacting, but not depressed against, anobject produces no striking force which could cause inadvertent damage.

A modified form of the invention for inserting drive rivets is shown inthe punch gun apparatus, generally indicated by the numeral 110, in FIG.7. The structure and operation of the barrel 111 and other componentsare identical to that described above, except as hereinafter noted. Amodified punch 128 is substituted for the punch 28 by removing andsubsequently replacing the punch housing 115. The modified punch 128 hasa blow receiving base 129 and an enlarged collar 130' which tapers toform a punch shaft 131. As shown, the shaft 131 is shorter than shaft 31and without a tip portion 31'. The shaft 131 is of such a length so asto engage the extremity of a rivet generally indicated by the numeral170, and particularly the driven shaft 171 which moves into hollowhousing 172 and splays it open radially along the axial slot 173. Ifnecessary to accommodate different rivet sizes, the dimensions ofreceiver and punch 128 could be varied by providing interchangeableparts.

We claim:

1. Apparatus for piercing sheet material comprising, barrel means,piston means housed in a first bore in said barrel means, punch meanshoused in a second bore in said barrel means which communicates with thefirst bore means, spring means forcing said piston means toward saidpunch means, biasing means urging said punch means away from said pistonmeans and outwardly of the barrel means, cocking means compressing saidspring means, trigger means selectively releasing said piston means tostrike said punch means and operable independent of the position of saidpunch means.

2. Apparatus according to claim 1, wherein said piston means has acollar engaging a neck in the first bore to restrict the travel of saidpiston means to strike said punch means only when said punch means isdepressed against said biasing means.

3. Apparatus according to claim 2, wherein a portion of said pistonmeans extends into the second bore to selectively strike said punchmeans.

4. Apparatus according to claim 2, wherein said biasing means is a coilspring.

5. Apparatus according to claim 1, wherein said cocking means compriseshandle means, a portion of said handle means engaging said piston meansand movably mounted to displace said piston means to compress saidspring means.

6. Apparatus according to claim 5, wherein a portion of said handlemeans is pivotably mounted by a dual hinge and has a bifurcated portionfreely rotatably mounting a bearing pin selectively positionedlongitudinally of said piston means.

7. Apparatus according to claim 5, including a sear plate pivotable intothe first bore in said barrel means to engage a collar on said pistonmeans and maintain said piston displaced with said spring meanscompressed.

8. Apparatus according to claim 7, wherein said trigger meanscooperatively engages said sear plate, whereby actuation of said triggerrotates said sear plate to release said piston means.

9. Apparatus according to claim 8, wherein said trigger has a shoulderwhich engages a lip on the sear plate.

10. Apparatus according to claim 9, including a sear plate springpivotally urging said sear plate against said trigger and toward saidpiston means.

References Cited UNITED STATES PATENTS 913,677 3/1909 Ainsworth 30367v3,181,626 5/1965 Sussman 173119 X FOREIGN PATENTS 636,889 3/1928France.

ERNEST R. PURSER, Primary Examiner U.S. Cl. X.R.

